RTC of LPC1768 sometime works sometime not.

[santoshkatke]

Greetings,

I am using LPC1768 in my project. Everything goes fine except internal RTC. I have kept 1sec RTC interrupt upon which i am displaying date and time on GLCD but RTC interrupt stops after some time and then again after some time it starts where last time stopped. I found that 32KHz crystal stops oscillating after some time,when i checked wave forms on scope. I have checked for any dry solder and values of capacitors which are ok, replaced 32KHz crystal as well. So what could be the reason of this behaviour.

Thanks in advance.

[kerryzhou]

Hello Santosh Katke,

    The LPC1768 RTC don't work reliably problem seems the existing problem, because I have found it in the LPC176X errata.

http://www.nxp.com/docs/en/errata/ES_LPC176X.pdf 

Still no work-around.

   But you said the external crystal stops oscillating, I think it also relate to the external crystal hardware, you may try to change the load capacitor, and test it again.

Have a great day,
Kerry

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